9.28: Consider a demand-paging system with the following time-measured utilizati
ID: 3764603 • Letter: 9
Question
9.28: Consider a demand-paging system with the following time-measured utilizations: CPU utilization 20% Paging disk 97.7% Other I/O devices 5 %
For each of the following, say whether it will (or is likely to) improve CPU utilization. Explain your answers. a.) Install a faster CPU. b.) Install a bigger paging disk. c.) Increase the degree of multiprogramming. d.) Decrease the degree of multiprogramming. e.) Install more memory. f.) Install a faster hard disk or multiple controllers with multiple hard disks.
Explanation / Answer
The system obviously is spending most of its time paging, indicating over-allocation of memory. If the level of multiprogramming is reduced resident processes would page fault less frequently and the CPU utilization would improve. Another way to improve performance would be to get more physical memory or a faster paging drum.
a.) Install a faster CPU. -- No
b.) Install a bigger paging disk.-- No
c.) Increase the degree of multiprogramming. -- No
d.) Decrease the degree of multiprogramming.-- Yes
e.) Install more memory. --Likely to improve CPU utilization as more pages can remain resident and not require paging to or from the disks.
f.) Install a faster hard disk or multiple controllers with multiple hard disks.---Also an improvement, for as the disk bottleneck is removed by faster response and more throughput to the disks, the CPU will get more data more quickly.
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